The present invention relates to a guide rail for a window regulator and a slide-guide mechanism employing the same, and more particularly to a guide rail for the window regulator which is rigid in spite of being made of a thin metal sheet and to a slide-guide mechanism for a window regulator employing the light guide rail in which play is small when it moves slidably.
Hitherto, a slide-guide mechanism comprising a bracket secured to a window glass and a guide rail secured to a door of an automobile, or the like is employed as a window regulator of an automobile, or the like. In such a slide-guide mechanism, the bracket is slidably moved by a wire secured to the bracket and extending in longitudinal direction of the guide rail and by a driving mechanism for winding up or off the wire. In such a guide rail for a window regulator, a guide rail having a C-shape in section (FIG. 6) is well known. The guide rail is formed out of a thin hoop sheet 101 (e.g. 1.2 millimeters in thickness) by bending both side edges 101a in the same direction and at right angle with the hoop sheet 101, and further bending inside edges 101b of the side edges 101a in almost parallel to the hoop sheet. In the case of the window regulator having such a guide rail, the rigidity for guiding the window glass is not sufficient. More particularly, such a guide rail has a disadvantage that the rigidity against the bending moment around the binormal axis of the window glass is not sufficient. Thereby, when it is used in the type of the window in which the window glass is not guided by a window frame, there is a defect that the window glass tends to incline forward. Therefore, an increase in the rigidity of the guide rail for the window regulator is needed. On the other hand, a guide rail (FIG. 7) having a U-shape in section suggested by U.S. Pat. No. 3,427,748 is also known. The guide rail is formed out of a thick hoop sheet 111 (e.g. 2.0 millimeters in thickness) by bending side edges 111a in the same direction and at right angle with the hoop sheet 111. However, it has disadvantages that the guide rail is heavy and the cost of the material is expensive.
Also, as a slide-guide mechanism employed in the window regulator, the slide-guide mechanism comprising said guide rail 101 having C-shape in section and the bracket 102 having slide shoes 106 which are arranged so as to enclose the guide rail is known. However, it is difficult to accurately keep the distance L (FIG. 8) between the side edges of such a guide rail due to the limitation of the processing method, because the side edges 104 of effective guiding faces are processed by press-forming or roll-forming. Therefore, it is required to provide a proper clearance C (FIG. 8) between the bracket and the guide rail, so that the bracket can slidably move along the guide rail. In the case that the window glass is slidably guided by a sash, the problems are few. However, in the not-sufficiently-guided window glass, e.g. a trapezoid-shaped window glass of a front door of an automobile or a window glass of a hard-top car having no center pillar, the clearance mentioned above causes play in the window glass. Particularly, because the window glass of the front door is guided only by the rear sash, the window glass tends to incline forward. Therefore, noise generated by the vibration of a running automobile can be annoying to the passengers. Further, the not-sufficiently-guided window glass has a disadvantage that the vibration can damage the window regulator or the sash.
The slide-guide mechanism in which the above-mentioned disadvantages are eliminated is suggested by U.S. Pat. No. 3,427,748, as shown FIG. 9. This suggested mechanism comprises a guide rail 201 of L-shaped section and a bracket 202 having a slide member 206 provided with a slit 207 which has the width almost equal to the thickness of a guide member 204, i.e. the thickness of the metal sheet of the guide rail 201. Because the thickness of the guide member 204 is equal to that of the metal sheet of the guide rail 201, this mechanism has an advantage that the thickness is very accurate and thereby the clearance can be decreased to the minimum necessary. However, this mechanism does not have sufficient rigidity, particularly against the bending moment around the binormal axis of the window glass. Therefore, the thickness of the plate is required to be more thickened for giving the sufficient rigidity than that needed to certainly guide the window glass. Therefore, this mechanism has disadvantages that the cost and the weight of the whole slide-guide mechanism increase.